1. Field of the Invention
The present invention relates to a residual capacity detection method and device for a fuel cell battery using hydrogen or the like as fuel.
2. Description of the Related Art
The application of fuel cell batteries using hydrogen or methanol can be considered as fuel cell batteries for various information processing apparatuses because of their light weight and convenience. As such information processing apparatuses, for example, there are digital cameras, camcorders, notebook-sized personal computers, cellular phones, personal digital assistants (PDAs), audio players, electronic devices having a communication function such as capsule-type medical devices, etc.
With a hydrogen storage container using a hydrogen storage material and a fuel cell system using the same, there is proposed a fuel cell system used especially for portable equipment.
For example, Japanese Patent Application Laid-Open No. 2004-362786 teaches a fuel cell system for portable equipment, in which an outgassing mechanism has a similar structure to a pressure control mechanism, and consists of a hydrogen relief valve using a piezoelectric substance and a flow path. This system has a primary pressure sensing mechanism for sensing hydrogen pressure in a hydrogen storage alloy container, and a pressure control circuit for controlling the action of the hydrogen relief valve using the piezoelectric element. In this structure, when the hydrogen pressure in or temperature of a hydrogen storage container exceeds a prescribed value, the pressure control circuit applies voltage to the hydrogen relief valve of piezoelectric substance to discharge hydrogen gas to the outside in order to assure that the discharge of the hydrogen gas is safe.
Further, Japanese Patent Application Laid-Open No. 2006-99984 discloses electronic equipment having a tank part in which a plurality of hydrogen storage alloys different in hydrogen desorption properties are housed. In this tank part, the hydrogen storage alloys, a pressure sensor, an output circuit, and a temperature sensor are included. This is electronic equipment using a fuel cell battery having a power generation part for generating electric power using hydrogen discharged from the tank part, a pressure detection part for detecting the pressure of hydrogen supplied to the power generation part, and a residual amount sensing part for detecting the residual amount of hydrogen based on the hydrogen desorption properties of the plurality of hydrogen storage alloys by means of the pressure detection part.
Further, Japanese Patent Application Laid-Open No. 2004-241261 describes a fuel cell battery having a temperature sensor for measuring the temperature of a hydrogen storage alloy in a hydrogen storage alloy tank in which the hydrogen storage alloy of the fuel cell battery is housed, a hydrogen flow path for supplying hydrogen from the hydrogen storage alloy tank to the fuel cell battery, and a pressure sensor for measuring hydrogen pressure in the hydrogen flow path. In this publication, a measurement method for determining the hydrogen storage capacity of the hydrogen storage alloy as a function representing a relationship between hydrogen pressure and residual hydrogen amount at each temperature predetermined in experiments is disclosed in connection with a graph representing the function.
Further, in “Fuel Control Micro-Valve for Portable Fuel Cells,” Matsushita Technical Journal, Vol. 53 No. 4, there is disclosed such a technique that MEMS (Micro Electro Mechanical Systems) technology and an electrostatic drive system are used for a micro-valve to achieve a normally closed state as a fuel control valve for portable fuel cells to limit power consumption only during electric power generation.